1. Field of the Invention
The present invention relates to a Stirling cooler, and more particularly to a Stirling cooler, in which an inner stator can be structurally attached and detached from a cylinder.
2. Description of the Related Art
Generally, a Stirling cooler is an external combustion engine using a reverse cycle of the Stirling cycle.
FIG. 1 is a cross-sectional view of a conventional Stirling cooler. FIG. 2 is an exploded perspective view of an essential part of the conventional Stirling cooler.
The conventional Stirling cooler comprises a case 4 provided with a cold tip 2 at an opened end thereof, a cylinder 6 fixedly installed in the case 4 and filled with a fluid, a piston 8 installed in the cylinder 6 such that the piston 8 can reciprocate and provided with a hollow 7 formed therein, a displacer 10 installed in the hollow 7 of the piston 8 such that the displacer 10 can reciprocate, a regenerator 12 longitudinally connected to the displacer 10, and provided with a cavity 1 positioned between the regenerator 12 and the cold tip 2 and filled with the fluid, and a heat exchanger 14 connected to the cylinder 6 and the regenerator 12.
The piston 8 is connected to a linear motor (M) installed between the case 4 and the cylinder 6, and reciprocates. The displacer 10 is connected to an elastic member 16 installed in the case 4 such that the displacer 10 faces the regenerator 12, thus being elastically supported such that the displacer 10 faces the cold tip 2. A hole 11 is formed in a lower part of the regenerator 12, opposite to the cold tip 2.
The linear motor (M) includes an outer stator 20 fixed to an inner surface of the case and connected to an external power source, an inner stator 30 positioned within the outer stator 20 and fixed to an outer surface of the cylinder 6, and a magnet 40 installed between the inner stator 30 and the outer stator 20 such that the magnet 40 can reciprocate in an axial direction of the cylinder 6 and be interworked with the piston 8.
The outer stator 20 includes a bobbin 22, a coil 24 wound on the bobbin 2 so that external power is applied to the coil 24, and a core 26 obtained by stacking a plurality of steel sheets along a circumferential direction of the bobbin 22 and surrounding the outer surface of the bobbin 22 wound with the coil 24.
The inner stator 30 includes a core 32 obtained by stacking a plurality of steel sheets along the circumferential direction of the bobbin 22, and a pair of end rings 34 and 36 respectively inserted into both ends of the core 32 for maintaining the shape of the core 32. The inner stator 30 is attached to an outer circumference of the cylinder 6 by an adhesive agent.
Hereinafter, operation of the above-described conventional Stirling cooler will be described in detail.
When power is applied to the coil 24 of the outer stator 20, an electromagnetic field is formed between the outer stator 20 and the inner stator 30, and the magnet 40 moves toward the cold tip 2 by means of the interaction of the electromagnetic field and the magnet 40.
Since the piston 8 is interworked with the magnet 40, the fluid of the cylinder 6 is isothermally compressed, is discharged from the heat exchanger 14 to emit heat, and is introduced into the regenerator 1 to emit sensible heat. Then, the fluid fills the cavity 1 between the regenerator 12 and the cold tip 2 and is isothermally expanded simultaneously. Here, as the fluid fills the cavity 1 between the regenerator 12 and the cold tip 2, the regenerator 12 and the displacer 10 move away from the cold tip 2.
Thereafter, when the direction of the power applied to the coil 24 of the outer stator 20 is changed, the magnet 40 together with the piston 8 moves away from the cold tip 2, and the displacer 10 and the regenerator 12 are returned to their earlier positions toward the cold tip 2 by the elastic force of the elastic member 16. The fluid filling the cavity 1 between the regenerator 12 and the cold tip 2 subsequently passes through the regenerator 12 and the heat exchanger 14 to absorb heat, and then re-fills the cylinder 6.
Since the cylinder 6 and the stator 30 must be supported by a jig while the inner stator 30 contacts the outer surface of the cylinder 6, and it is difficult to detach the inner stator 30 from the cylinder 6, the conventional Stirling cooler has a poor workability. Further, the fluid of the cylinder 6 chemically reacts with the adhesive agent applied between the cylinder 6 and the inner stator 30, thus causing contamination to the Stirling cooler.